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Relationship between nano-scale deformation of coal structure and metamorphic-deformed environments

Chinese Science Bulletin 2005年第16期50卷 1784-1795页

作者： JU Yiwen JIANG Bo HOU Quanlin WANG Guiliang College of Mineral Resource and Geosciences China University of Mining and Technology Xuzhou 221008 China laboratory of computational {2. College of Geosciences Graduate University of Chinese Academy of Sciences Beijing 100049. China

There is a more consanguineous relation be-tween nano-scale deformation of coal structure and meta-morphic-deformed environment. In different metamor-phic-deformed environments, deformation in the coal struc-ture can occur not only at micro-scale, but also at nano-scale, and even leads to the change of molecular structure and nano-scale pore (<100 nm) structure. The latter is the main space absorbing coalbed methane. Through X-ray diffraction (XRD) and liquid–nitrogen absorption methods, the charac-teristics of macromolecular and nano-scale pore structures of coals in different metamorphic-deformed environments and deformational series of coals have been studied. By combin-ing with high-resolution transmission electron microcopy (HRTEM), the macromolecular and nano-scale pore struc-tures are also directly observed. These results demonstrate that the stacking Lc of the macromolecular BSU in tectonic coals increases quickly from the metamorphic-deformed environment of low rank coals to that of high rank coals. For different deformed tectonic coals, in the same metamor-phic-deformed environment, the difference of Lc is obvious. These changes reflect chiefly the difference of different tem-perature and stress effect of nano-scale deformation in tec-tonic coals. The factor of temperature plays a greater role in the increase of macromolecular structure parameters Lc, the influence of stress factor is also important. With the stress strengthening, Lc shows an increasing trend, and La /Lc shows a decreasing trend. Therefore, Lc and La /Lc can be used as the indicator of nano-scale deformation degree of tectonic coals. With increasing temperature and pressure, especially oriented stress, the orientation of molecular structure be-comes stronger, and ordering degree of C-nets and the ar-rangement of BSU are obviously enhanced. For the deforma-tion of nano-scale pore structure, in the same metamor-phic-deformed environment, along with the strengthening of stress, the ratio of m

关键词：煤结构纳米变形大分子结构地质环境

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The inversion of density structure by graphic processing unit(GPU) and identification of igneous rocks in Xisha area

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Earthquake Science 2014年第1期27卷 117-125页

作者： Lei Yu Jian Zhang Wei Lin Rongqiang Wei Shiguo Wu laboratory of computational {2. University of Chinese Academy of Science School of the Earth Science University of Chinese Academy of Science Institute of Oceanology Chinese Academy of Sciences

Organic reefs, the targets of deep-water petro- leum exploration, developed widely in Xisha area. However, there are concealed igneous rocks undersea, to which organic rocks have nearly equal wave impedance. So the igneous rocks have become interference for future explo- ration by having similar seismic reflection characteristics. Yet, the density and magnetism of organic reefs are very different from igneous rocks. It has obvious advantages to identify organic reefs and igneous rocks by gravity and magnetic data. At first, frequency decomposition was applied to the free-air gravity anomaly in Xisha area to obtain the 2. subdivision of the gravity anomaly and magnetic anomaly in the vertical direction. Thus, the dis- tribution of igneous rocks in the horizontal direction can be acquired according to high-frequency field, low-frequency field, and its physical properties. Then, 3D forward model- ing of gravitational field was carried out to establish the density model of this area by reference to physical properties of rocks based on former researches. Furthermore, 3D inversion of gravity anomaly by genetic algorithm method of the graphic processing unit （GPU） parallel processing in Xisha target area was applied, and 3D density structure of this area was obtained. By this way, we can confine the igneous rocks to the certain depth according to the density of the igneous rocks. The frequency decomposition and 3D inversion of gravity anomaly by genetic algorithm method of the GPU parallel processing proved to be a useful method for recognizing igneous rocks to its 3D geological position. So organic reefs and igneous rocks can be identified, which provide a prescient information for further exploration.

关键词： Xisha area Organic reefs and igneous rocks -Frequency decomposition of potential field 3D inversionof the graphic processing unit (GPU) parallel processing

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Active tectonics in Taiwan:insights from a 3-D viscous finite element model

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Earthquake Science 2015年第5期28卷 353-363页

作者： Yujun Sun Mian Liu Shuwen Dong Huai Zhang Yaolin Shi Institute of Geomechanics Chinese Academy of Geological Sciences Key laboratory of computational {2. Chinese Academy of Sciences Department of Geological Sciences University of Missouri Chinese Academy of Geological Sciences

Taiwan is a young orogenic belt with complex spatial distributions of deformation and earthquakes. We have constructed a three-dimensional finite element model to explore how the interplays between lithospheric struc- ture and plate boundary processes control the distribution of stress and strain rates in the Taiwan region. The model assumes a liberalized power-law rheology and incorporates main lithospheric structures; the model domain is loaded by the present-day crustal velocity applied at its bound- aries. The model successfully reproduces the main features of the GPS-measured strain rate patterns and the earth- quake-indicated stress states in the Taiwan region. The best fitting model requires the viscosity of the lower crust to be two orders of magnitude lower than that of the upper crust and lithospheric mantle. The calculated deviatoric stress is high in regions of thrust faulting and low in regions of extensional and strike-slip faulting, consistent with the spatial pattern of seismic intensity in Taiwan.

关键词： Taiwan Stress Strain rate FEM model Earthquake

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Focal mechanisms of the Lushan earthquake sequence and spatial variation of the stress field

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Science China Earth Sciences 2015年第4期58卷 1148-1158页

作者： LUO Yan ZHAO Li ZENG XiangFang GAO Yuan Institute of Earthquake Science China Earthquake Administration Institute of Earth Sciences Academia Sinica Key laboratory of computational {2. Chinese Academy of Sciences

Using broadband seismic records from regional networks, we determined the focal mechanisms and depths of 37 earthquakes in the 2.13 M7.0 Lushan earthquake sequence(3.4≤Mw≤5.1) by fitting the three-component waveform data. The results show that the earthquakes are predominantly thrust events, with occasional strike-slip mechanisms. Most earthquakes occurred at depths of 10–2. km. We derived the regional distribution of the average stress field in this area using the damped linear inversion method and the focal mechanisms obtained in this study. The inversion results suggest that the Lushan region and the adjacent area are mostly under compression. The orientations of the maximum principal axes trend NW-SE, with some local differences in the stress distribution at different depths. Compared with the distribution of the stress field in the Wenchuan earthquake area, the stress field in the southwest section of the Longmenshan Fault zone(LFZ) share similar characteristics, predominantly thrust faulting with a few strike-slip events and the maximum compression axes being perpendicular to the LFZ.

关键词： Lushan earthquake focal mechanisms stress field aftershock sequence

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Dynamic simulation of interactions between major earthquakes on the Xianshuihe fault zone

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Science China Earth Sciences 2008年第10期51卷 1388-1400页

作者： WANG Hui LIU Jie SHI YaoLin ZHANG Huai ZHANG GuoMin Institute of Earthquake Science China Earthquake AdministrationBeijing 100036China laboratory of computational {2. Graduate University of Chinese Academy of SciencesBeijing 100049China China Earthquake Network Center China Earthquake AdministrationBeijing 100045China

The authors firstly evaluate the strain accumulation rate of the Xianshuihe fault zone based on earthquake activity. We calculated the stress and seismic moment accumulation rate for each subsection of the Xianshuihe fault zone based on the distribution of geological slip rate and GPS survey results. According to the results, we get the recurrence intervals of characterized earthquakes on each subsection respectively. A three-dimensional finite element model for western Sichuan is constructed to discuss the earthquakes triggering among major earthquakes ({ntM}>6.7) that occurred along the Xianshuihe fault zone since 1893. The calculated Coulomb failure stress changes (?CFS) show that 5 of the 6 earthquakes with Ms>6.7 were triggered by positive ?CFS. The interactions between major earthquakes not only influence recurrence intervals of characterized earthquakes on each subsection, but also change recurrence behavior of major earthquakes along the whole fault zone.

关键词： Xianshuihe fault zone strain accumulation and releasing recurrence interval finite element method Coulomb failure stress changes

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Modeling seismic wave propagation in heterogeneous medium using overlap domain pseudospectral method

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地震学报 2008年第1期30卷 47-58页

作者：严九鹏王彦宾 laboratory of computational {2. Department of Geophysics School of Earth and Space Sciences Pe-king University

Pseudospectral method is an efficient and high accuracy numerical method for simulating seismic wave propaga- tion in heterogeneous earth medium. Since its derivative operator is global, this method is commonly considered not suitable for parallel computation. In this paper, we introduce the parallel overlap domain decomposition scheme and give a parallel pseudospectral method implemented on distributed memory PC cluster system for modeling seismic wave propagation in heterogeneous medium. In this parallel method, the medium is decomposed into several subdomains and the wave equations are solved in each subdomain simultaneously. The solutions in each subdomain are connected through the transferring at the overlapped region. Using 2. models, we compared the parallel and traditional pseudospectral method, analyzed the accuracy of the parallel method. The results show that the parallel method can efficiently reduce computation time for the same accuracy as the traditional method. This method could be applied to large scale modeling of seismic wave propagation in 3D heterogeneous medium.

关键词：重叠区域分解算法傅里叶伪谱法并行计算地震波场

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Dynamics of unstable continental subduction:Insights from numerical modeling

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Science China Earth Sciences 2017年第2期60卷 218-234页

作者： HUANGFU PengPeng WANG YueJun FAN WeiMing LI ZhongHai ZHOU YongZhi School of Earth Science and Geological Engineering Sun Yat-sen University Key laboratory of computational {2. College of Earth SciencesUniversity of Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences Key Laboratory of Continental Collision and Plateau UpliftInstitute of Tibetan Plateau ResearchChinese Academy of Sciences

Numerical experiments are used in this study to systematically investigate the effects of convergence rate,crustal rheological strength,and lithospheric thermal structure on the dynamics of continental *** study focuses on the types,conditions and processes of unstable continental *** results suggest that the development of unstable continental subduction can be promoted by conditions that tend to decrease rheological strength of the lithosphere,such as low crustal rheological strength,"hot"thermal structure of the lithosphere,or low convergence *** subduction mode can be further categorized into three types:(1)multi-stage slab breakoff,(2.continuously"flowing"of fluid-like slab into the upper mantle,and(3)large-scale detachment of the thickened orogenic *** three types of unstable continental subduction are respectively associated with(1)a low convergence rate,(2."hot"thermal structure of the lithosphere with a high convergence rate,and(3)moderate-high crustal rheological strength with a low convergence *** is also revealed that the evolution of crustal melting is dominated by the deformation pattern of continental collision,which is mainly controlled by crustal rheological *** modelling results have important implications for understanding of continental subduction mode selection under specific geodynamic conditions.

关键词： Unstable continental subduction Stable continental subduction Slab breakoff Detachment Partial melting

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Discussion on origin of Pn velocity variationin China and adjacent region

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地震学报 2004年第1期26卷 1-10页

作者：裴顺平许忠淮汪素云 computational geodynamics {2. Department of Geophysics Peking University Institute of Geophysics China Seismological Bureau

Pn velocity lateral variation and anisotropy images were reconstructed by adding about 50 000 travel times from the regional seismic networks to the datum set of near 40 000 travel times from National Seismic Network of China used by WANG, et al. We discussed the relation of Pn velocity variation to Moho depth, Earths heat flow, distribution of Cenozoic volcanic rock and the result of rock experiment under high pressure and high temperature. The result of quantitative analysis indicates that Pn velocity is positively correlated with the crust thickness and negatively correlated with the Earths heat flow. Two linear regression equations, one between Pn velocity and crust thickness, and the other between Pn velocity and heat flow, were obtained. The rate of variation of Pn veloc-ity vP with pressure P, Pv/p, estimated from the velocity variation with crust thickness Hv/p, is close to the result obtained from the rock experiment under high pressure and high temperature. If the effect of crust thick-ness on Pn velocity is deducted from the velocity variation, then the low Pn velocity beneath Qinghai-Xizang pla-teau is more notable. The low Pn velocity regions well agree with the Cenozoic volcanic rock. In the several re-gions with significant anisotropy, the direction of fast Pn velocity is consistent with the orientation of maximum principal crustal compressive stress, and also with the direction of present-day crustal movement. It indicates that the fast Pn velocity direction may be related to the deformation or flow of top mantle material along the direction of maximum pressure.

关键词：地震台网 Pn波地壳厚度新生代火山岩各向异性层析成像

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Numerical simulation of temporal and spatial evolution of fold-thrust belts in the northern and northeastern margins of the Qinghai-Tibetan Plateau

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Earthquake Research Advances 2021年第S1期1卷 23-25页

作者： Qizhi Chen Caibo Hu School of Earth and Planetary Sciences University of Chinese Academy of SciencesKey Laboratory of Computational GeodynamicsChinese Academy of SciencesBeijingChina

Fold-thrust belts are common structural styles under the background of long-term regional tectonic *** northern and northeastern margins of the Qinghai-Tibetan Plateau are located on the edge of the growth and expansion of the Qinghai-Tibetan *** nearly 10 Ma,some significant and typical fold thrust belt have been *** spatial-temporal evolution of these fold-thrust belts and the characteristics of surface deformations are significant issues in *** this paper,we use the elastoplastic finite element model with considering the contact nonlinearity to study the spatialtemporal evolution of the fold-thrust belts in the northern and northeastern margins of the Qinghai-Tibetan Plateau,with particular attention to the details of the relationship between the depth and the shallow,the spatialtemporal order,and the characteristics of the surface deformation,etc.,in order to make a relatively complete mechanical interpretation of the spatial-temporal evolution of the foldthrust belts in the northern and northeastern margins of the Qinghai-Tibetan Plateau from the perspective of geodynamics.

关键词： Fold-thrust belts Finite element model Elastoplasticity Northeastern margin of the Qinghai-Tibetan Plateau Frictonal contact

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Co-seismic Earth's rotation caused by the 2.12.Sumatra earthquake

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Geodesy and geodynamics 2012年第4期3卷 28-31页

作者： Xu Changyi Sun Wenke Key laboratory of computational {2. University of Chinese Academy of Sciences

Earthquakes heavily deform the crust in the vicinity of the fault, which leads to mass redistribution in the earth interior. Then it will produce the change of the Earth＇s rotation （ polar motion and length of day） due to the change of Earth inertial moment. This paper adopts the elastic dislocation to compute the co-seismic polar motion and variation in length of day （LOD） caused by the 2.11 Sumatra earthquake. The Earth＇s rota- tional axis shifted about 1 mas and this earthquake decreased the length of day of 1 p,s, indicating the tendency of earthquakes make the Earth rounder and to pull the mass toward the centre of the Earth. The result of varia- tion in length of day is one order of magnitude smaller than the observed results that are available. We also compared the results of three fault models and find the co-seismic change is depended on the fault model.

关键词： earthquake Earth rotation polar motion variation in LOD

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